1. Field of the Invention
The present invention generally relates to medical devices, and more particularly, relates to medical devices for treatment of undesirable deposits within the body of a patient.
2. Description of the Prior Art
Procedures and apparatus have been developed for ease in removing tissue and various deposits. U.S. Pat. No. 4,790,813 issued to Kensey and U.S. Pat. No. 4,842,579 issued to Shiber describe techniques for the removal of plaque deposited in arteries by mechanical ablation using rotating cutting surfaces. These relatively traumatic approaches are directed to the treatment and removal of very hard substances.
Pressurized fluids have also been used in the past to flush undesirable substances from body cavities. U.S. Pat. No. 1,902,418 describes such a system for flushing body cavities of domesticated animals. The more modern references tend to use vacuum rather than gravity as the primary means for removal of the deposits or tissue and relatively low fluid pressures for ablation.
U.S. Pat. No. 3,930,505 issued to Wallach describes a surgical apparatus for the removal of tissue from the eye of a patient. As with similar systems, Wallach uses a relatively low pressure jet of water (i.e. 15 to 3500 psi) to disintegrate the tissue, and a suction pump to perform the actual removal.
A similar approach applied to the cardiovascular system is discussed in U.S. Pat. No. 4,690,672 issued to Veltrup. Veltrup also provides a much lower pressure jet of water (i.e. less than 450 psi) to flush the deposits. As with Wallach, Veltrup uses a vacuum pump for evacuation of the fragments. It seems apparent that the prior art uses only relatively low pressure jets for safety reasons. Furthermore, most of the prior art devices are not suitable to treat fully occluded vessels as they require a portion of the device to transit the lesion.